Aos 3 -> aos 4

[HammerD]

In my case, OS4 isnt able to do what my Classic 68k 3.9 does. For example:

I use USB 2.0 (with OS4 I cant)

If your Classic Amiga has Zorro III you can get USB 2.0 with the Deneb card.  It works with the Poseidon USB stack under AmigaOS 4.0 or 4.1 Classic.

But obviously due to the limitations of Zorro III (and even worse Zorro II) you won't get anywhere near the 480Mbps of USB2 high speed.

[HammerD]

And Deneb won't do DMA on OS4 due to OS4 incompatibility/limitations dealing with perfectly fine DMA OS3 drivers.  BlizzardPPC/A4000T scsi situation is worse because it won't work at all.

It's not about any OS4 "limitations", but rather a different way the OS4.x memory system handles DMA.  A scatter/gather method of DMA would have to be implemented as that is how it is done under OS 4.x (to my knowledge).

It could be done with a firmware/driver update on the Deneb.

Same for blizzard or A4000T scsi - we just need a driver written natively for OS4.1.